This invention relates in general to a device for controlling the flow of fuel to an engine so as to prevent its operation. More particularly, this invention relates to a device which imparts information to the host computer of a vehicle which, in turn, shuts off or opens the fuel or ignition circuit of the vehicle, thereby cutting off or permitting the flow of fuel to the engine. The device can be selectively actuated and may be effective as a device to prevent auto theft, i.e., an anti-theft device, or as a device for limiting or restricting use of the vehicle into which it is installed.